I GOT IT RUNNING!!! ....poorly...

[fonzogt25]

ok, so i got my mustang running finally. it has a 71 351c in it. we managed to get it started today but, the timing seems be going all over. my family friend who is very knowledgeable on cars said that it was bouncing around it seems. it also kinda sounds like one cylinder isnt firing as well or at all as others.

anyway, i was hoping on some ideas or suggestions.

first im going to start with getting blue streak points, cap, rotor, and probably spark wires.

heres a video of the engine running: https://vid.me/HvG3

 

[72HCODE]

first i would do a compression check on all 8 and see if you have one cylinder or more with an issue.

if that checks out then i would shell out the money for a tune up.

when you pull the plugs look at them and see if any are damaged or have oil on them. that would also help pinpoint a problem to check with a compression test.

if the mechanical is good then you can focus on electrical.

my opinion, don't buy any aftermarket hop up parts, the OEM spec wires and plugs and distributor caps are excellent even for performance use.

buy normal spark plugs, autolite/motorcraft, 24/25 heat range(25 is stock)

get some stock points to start out, accel is good or oem style.

normal carbon filament ignition wires no fancy 8-10mm helicore wires just nice stock oem spec wires.

its impossible to find a stock ignition coil everything is high power now, so you might want to think about a electronics ignition install.

or try to get a nice accel or MSD coil that is compatible with a future upgrade to electronic ignition. a petronixs flamethrower coil is fine also.

take note of the engine timing before you start working if there as a mark on the balancer make note of it and aim for it when you complete the tune up.

 

[Don C]

Just running rough can cause the timing to bounce around, especially if the vacuum hose is still connected to the vacuum advance on the distributor. If the RPMs are high enough the mechanical advance could be causing it too, as the misfiring causes the RPMs to vary.

I would follow 72HCODE's troubleshooting advice.

One additional thing I would do while you have all of the spark plugs out is to check how loose the timing chain is. Do this by slowly turning the engine clockwise with a breaker bar with a socket on the crankshaft damper bolt to verify the distributor shaft/rotor is turning. Mark the location of the damper. Then watch the distributor shaft/rotor while you slowly turn the engine backwards (counterclockwise) by with the breaker bar to see how far the crankshaft turns before the camshaft and distributor begin to turn. If it's more than 5° your timing has too much slack.

 

[fonzogt25]

ok, so the vacuum advance was plugged in, so when i try again i will definately have that plugged up and that will hopefully help.

i ordered new spark plug wires, cap, rotor, and a pertronix ignitor I. all of those that i had were pretty wimpy and pretty cheap so im sure they werent helping with getting good spark.

now i have a question with the pertronix. when installing i dont have an internally resisted ignition coil. so do i need to run an external resistor from the ignitor to the coil? or can i just run without a resistor. i remember vaguely about something about a pink wire being resistance or something on here before

 

[will e]

Get yourself a timing light to verify initial timing. You can also use this to 'test' each cyl wire to verify if they are firing consistently.

An adjustable timing light will show you how much mechanical advance you have and you can also determine your vacuum advance too. If you use a hand pump you can see when/how much the vacuum advance goes. And most adjustable timing lights will have a digital rpm indicator. Again, a great way to check each cyl is firing consistently (they should all indicate about the same rpm)

 

[fonzogt25]

so i did a compression test today, each cylinder is about 125-140. cylinder 4 however is only at 112. i put a little oil in there and tried again and it stayed the same, so i believe that means its a valve? i will probably fix that in the winter though, i dont think it will make a huge difference while running and timing it.

Will e, my friend had a timing light and he looked at it and figured it all out. hes more knowledgeable than me so i let him take the lead on it. i cant remember how much he said it was varying, i think 30 degrees or something, but that was before i changed all the electrical and unhooked the vacuum advance

is anyone sure of the pertronix set up?

 

[will e]

The 112 is on the hairy edge of acceptable variance. It could be a valve or head gasket. Worse case worn rings or cracked piston (not likely). It may actually make running/timing it a little more complex. It's interesting that adding oil didn't help.